1. Field of the Invention
The present invention relates to cooling systems for a boat having an outboard motor and engine.
2. Description of the Related Art
Known outboard motors mix ambient air entering through the engine's cowling with fuel. The air/fuel mixture is burned in one or more cylinders of the motor to generate power and propel the boat. The output efficiency of the engine may decline if the temperature of the engine is not regulated. The air in the cowling must be replaced with fresh air to regulate the temperature of the engine.
U.S. Pat. No. 5,078,629 discloses a structure which inhibits moisture from mixing with the air for combustion. The specification states, “A transom board of the hull has an opening and a cowling of an outboard motor has an air port for taking air for combustion. The opening and the air port are connected to each other through a duct; thereby, air is taken from a location in the hull.” “The air hardly contains moisture in comparison with the case in which the cowling of the outboard motor has an intake opening and air is taken through the intake opening.” With this structure, combustion air enters through an opening in the transom board. The specification discloses drawing combustion air through the transom, not cooling air.
Patent Document JP-A-2004-239156 discloses a structure that ventilates the cowling of an outboard motor. The specification states, “a boat provided with an outboard motor having a cowling including a bottom cowl with a ventilating air inlet opening downward for introducing outside air, a maze-structure ventilation separator with a zigzag flow path for separating and removing foreign objects, such as moisture, from the outside air, and a ventilating fan combined with a flywheel and essentially made up of fins” (see paragraphs [0092] and [0093], and reference numerals 438 and 439 in FIG. 2). The disclosed structure flows air upwards in the engine compartment. However, the ventilating air inlet is formed through the bottom cowl of the cowling of the outboard motor. Since the outboard motor is placed on water, water may enter through the ventilating air inlet. Further, the structure described in Patent Document JP-A-2004-239156 cannot completely prevent entry of water into the engine compartment when the air contains moisture or small water droplets. Such moisture may deteriorate engine function.
In the cooling system above, moisture from waves may still mix with the air as the air is routed through the engine compartment.